June 21st, 2010 | 
Author: I have 3 black n decker 12v drills (had one before I married, my husband had one already and we have a swivel head one too). I have a brand new battery (bought yesterday) as well as 3 older batteries. I have 3 chargers total and Not one of them will charge the batteries (new or old ones) adequately enough to drill even one hole in my cabinet. I have even tried charging them overnight. Two chargers are the type that plug into the drill itself when the battery is attached. The other charger is separate from the drill and holds a single battery pack. The separate charging pack has a red light on it but it does not light up. I have plugged them into multiple different a/c outlets.
Posted in Cordless Drill Batteries | Tags: Batteries, Battery Pack, Black N Decker, Chargers, red light, Swivel Head
It sounds like your chargers are shot. The ones that come with the drills aren’t very good and don’t last. B&D sells a multi-volt charger which is much better made than the ones that come with the drills. Can’t remember what its voltage range is but it works on my 14.4 volt batteries.
Charge it properly and cycle it properly.
NiCd batteries need to be fully cycled or they will develop a memory. Lithium batteries may be short-cycled but do have a spontaneous discharge rate of a few percent per day and so will eventually drain completely even ‘just sitting there’ – but may be recharged or left on the trickle-charger indefinitely.
As it happens, pretty much every battery does have some spontaneous discharge rate although NiCds are better than others this way, so it is best to anticipate that condition and plan to charge your batteries before each use.
Your chargers may be bad. It doesnt take much to ruin one. Check the voltage output with a digital multimeter.
Possible warranty problem. Check manufacturer web site for info.
cool#9
Sounds to me like you need new chargers , or have you checked the contacts where the charger and battery make contact, could the contact on the charger need cleaning?